JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.0/css/bootstrap.min.css">
<div>
    <input id="first_name" class="validate form-control" type="text" name="first_name" placeholder="First Name" />
    <div id="error_first_name" class="validator err alert alert-danger">The first name may only contain letters.
        <br />The first name must be at least 2 characters.</div>
</div>
<div>
    <input id="first_name" class="validate form-control" type="text" name="first_name" placeholder="First Name" />
    <div id="error_first_name" class="validator err alert alert-danger">The first name may only contain letters.
        <br />The first name must be at least 2 characters.</div>
</div>

JavaScript

$(".validate").keyup(function (e) {
    console.log($(this).siblings('.validator'));
    $(this).siblings('.validator').fadeOut();
});